Rik van Riel wrote:> Nick Piggin wrote:> >> Rik van Riel wrote:>>>>> With lazy freeing of anonymous pages through MADV_FREE, performance of>>> the MySQL sysbench workload more than doubles on my quad-core system.>>>>>> OK, I've run some tests on a 16 core Opteron system, both sysbench with>> MySQL 5.33 (set up as described in the freebsd vs linux page), and with>> ebizzy.>>>> What I found is that, on this system, MADV_FREE performance improvement>> was in the noise when you look at it on top of the MADV_DONTNEED glibc>> and down_read(mmap_sem) patch in sysbench.> > > Interesting, very different results from my system.> > First, did you run with the properly TLB batched version of> the MADV_FREE patch? And did you make sure that MADV_FREE> takes the mmap_sem for reading? Without that, I did see> a similar thing to what you saw...

Yes and yes (I initially forgot to add MADV_FREE to the down_readcase and saw horrible performance!)

> Secondly, I'll have to try some test runs one of the larger> systems in the lab.> > Maybe the results from my quad core Intel system are not> typical; maybe the results from your 16 core Opteron are> not typical. Either way, I want to find out :)

Yep. We might have something like that here, and I'll try withsome other architectures as well next week, if I can get glibcbuilt.